I have a sketch that works, finally. I want to use the Atmega chip from an Arduino, loaded with my sketch, to act as a slave I2C device in place of a Microchip 24LC00 EEPROM.
What is the MINIMUM amount of hardware I need to make the Atmega function as an I2C chip? Can I just pull the chip off the Arduino, hook up power, ground, SCL and SDA wires (or traces on a board, eventually) and have it work the same way it did on the Arduino board?
What is the MINIMUM amount of hardware I need to make the Atmega function as an I2C chip?
In general, an ATmega can get by with regulated 5V and nothing else. Check out this thread.
Can I just pull the chip off the Arduino,
If you want to get by that way, you need a 16MHz crystal and caps, a regulated voltage source, and pull-up resistor for the reset line. The IC alone won’t work without the support components that it is configured to expect.
The pullup resistor on reset is only neccy when connecting a reset switch (that is connected to ground) to prevent shorting that pin out.
The most minimal setup (w/out changing internal settings of the chip) really just needs a resonator or xtal & 2 caps. Even though Im sure Ive posted this elsewhere before, this is something I wrote up for my class on wiring up a breadboard arduino (assuming that the chip is programmed in the arduino board first):
Been meaning to do this for awhile anyway so I made a few changes, reformatted it, an added it to the playground:
Thanks - that's fantastic. Thank you very much.